Lubrication Characteristics of Water-Lubricated Rubber Bearings With Partial Wear

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Gang Liu ◽  
Ming Li
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Water Film ◽  
Eccentricity Ratio ◽  
Film Pressure ◽  
Water Film Thickness ◽  
Attitude Angle ◽  
Maximum Water ◽  
Lubrication Characteristics ◽  
Rubber Bearings

Abstract Water-lubricated rubber bearings are widely used in the propulsion shafting of military craft and ships. These bearings may wear down after a period of service, and consequently, their lubrication characteristics will change, affecting the operation of the shaft. Hydrodynamic lubrication characteristics of water-lubricated rubber bearings with partial wear at the bottom are studied by finite difference method. The steady-state characteristics of water-lubricated rubber bearings with wear and elastic deformation of rubber liner considered are solved with successive over-relaxation iteration method, and the dynamic characteristics are further calculated with finite perturbation method. The results show that water film thickness and distribution of water film pressure is significantly changed by wear. With the same eccentricity ratio, the maximum water film pressure, load capacity, attitude angle, and friction force are reduced by wear, but the friction coefficient is increased by wear. Under the same load, the minimum water film thickness and the maximum water film pressure are slightly affected by wear, the eccentricity ratio increases with the increase of wear, and the attitude angle and the friction coefficient decrease with the increase of wear. For large eccentricity ratios, the direct stiffness coefficients and direct damping coefficients are decreased by wear. The maximum allowable wear depth is approximately 1/6 of the bearing clearance.

Numerical Calculation Analysis of Structural Parameters of Water-Lubricated Thrust Bearing

2010 ◽  
Vol 44-47 ◽  
pp. 1666-1671 ◽  
Author(s):  
Lin Liu Zheng ◽  
Zhu Xin Wu
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Thrust Bearing ◽  
Structural Parameters ◽  
Water Film ◽  
Film Pressure ◽  
Water Film Thickness ◽  
Coefficient Increase ◽  
Maximum Water ◽  
Thrust Pad

The affect of the thrust pad inclination and ratio of length to breadth (L/B) on the lubricity of a water-lubricated thrust bearing is studied in numerical method. The research results indicate that when the elastic deformation is considered, the distribution of both water film thickness and pressure presents to be paraboloid. With the increase of thrust pad inclination, both maximum water-film pressure and the friction coefficient increase, and the minimum water-film thickness decreases first and then increases; when the L/B increases in the range of 1~2, both maximum water-film pressure and the friction coefficient increase, but the minimum water-film thickness decreases.

Effects on lubrication characteristics of water-lubricated rubber bearings with journal tilting and surface roughness

2019 ◽  
Vol 234 (2) ◽  
pp. 161-171
Author(s):  
Yuanying Du ◽  
Ming Li
Keyword(s):  
Surface Roughness ◽  
Film Thickness ◽  
Tilt Angle ◽  
Water Film ◽  
Film Pressure ◽  
Minimum Film Thickness ◽  
Pressure Peak ◽  
Roughness Amplitude ◽  
Lubrication Characteristics ◽  
Rubber Bearings

To study the effect of surface roughness on the lubrication characteristics of water-lubricated rubber bearings (WLRBs) when the stern shaft is tilted, the surface roughness of the bearings was measured by a surface roughness measuring instrument. Considering the tilting stern shaft and surface roughness, a mathematical model was constructed and water film thickness equation was deduced. By adopting the finite difference method, the film thickness and pressure distribution of WLRBs with tilt angle and roughness were analysed. The effects of tilt angle on film thickness and pressure under different surface roughness amplitudes and wavelengths were studied, and the results were then compared with those of smooth surface bearings without tilt angle. Finally, the minimum film thickness and maximum film pressure were analysed. The results showed that when the tilt of rotor and surface roughness of bearing were considered simultaneously, the film thickness exhibited a jagged distribution in the circumferential direction and decreased gradually in the axial direction. The film pressure had slightly irregular fluctuations and a sharp pressure peak. The tilt angle and roughness reduced the minimum film thickness, and the film thickness difference increased. The film pressure increased rapidly and local pressure exhibited slight, sudden changes. The surface roughness amplitude and wavelength had a considerable influence on the water film thickness, and the roughness amplitude had a clear effect on the film pressure. As the roughness amplitude increased, the minimum film thickness gradually declined and film pressure peak fluctuation grew. As the roughness wavelength increased, the film thickness fluctuated irregularly within a certain range of magnitude, and the minimum film thickness was almost constant.

The influence of road surface texture on the skid resistance under wet conditions

2018 ◽  
Vol 234 (3) ◽  
pp. 313-319
Author(s):  
Rebekka Kienle ◽  
Wolfram Ressel ◽  
Tobias Götz ◽  
Markus Weise
Keyword(s):  
Friction Coefficient ◽  
Film Thickness ◽  
Water Depth ◽  
Surface Texture ◽  
Water Film ◽  
Road Surface ◽  
Skid Resistance ◽  
Water Film Thickness ◽  
Pavement Surface ◽  
Wet Friction

Due to their influence on traffic safety, skid resistance and drainage are important surface properties of a road and their optimization and durability is still focus of ongoing research. Under wet conditions, these two characteristics are connected as a wetted road cannot provide a sufficient skid resistance without a working drainage system. The wet friction is mainly affected by the road surface geometry and the water depth. Herein, we describe a novel numerical approach to study the influence of the surface texture – mainly the microtexture – on the wet friction coefficient. This method is based on the hysteresis effect, which is the main friction force on rough surfaces under wet conditions. We therefore use an already established friction model for dry surfaces and extend its range of application by an additional consideration of water films. A drainage model has been developed to calculate the water film thickness for a given road surface and geometry (pavement surface runoff model) as systematic measurements of water film thicknesses in situ are difficult. The water depth determines the number of contact points between the pavement and the tyre. Based on three-dimensional measurements of a surface texture, the friction coefficient is calculated. By this newly developed model approach, it is possible to identify the main factors influencing wet skid resistance in regard to the pavement surface microtexture and the water film thickness.

scholarly journals Characteristic Analysis of Water Lubricated Plain Journal Bearing under Transient Load

2022 ◽  
Vol 2160 (1) ◽  
pp. 012073
Author(s):  
Pingwei Chen ◽  
Tong Wang ◽  
Wensheng Ma ◽  
Fangzhong Li ◽  
Tianzhou Wang ◽  
...  
Keyword(s):  
Film Thickness ◽  
Water Film ◽  
Characteristic Analysis ◽  
Film Pressure ◽  
Transient Load ◽  
Water Film Thickness ◽  
Minimum Value ◽  
Maximum Value ◽  
Value Of Water ◽  
Transient Loads

Abstract Transient load has a huge impact on the life and stability of water-lubricated bearings. In this paper work, CFD software is used to analyse the dynamic characteristic of water lubricated bearings under different transient loads of 500N, 1000N, 2000N and 3000N. The water film pressure contour distribution at different transient time was given. The time-varying relationships between the different transient loads with bearing forces, the journal displacement, the maximum value of water film pressure as well as the minimum value of water film thickness are obtained. The results show that with the increase of transient load, the effective bearing area of dynamic water pressure film decreases, and the maximum pressure increases. The bearing forces, the journal displacement, the maximum value of water film pressure as well as the minimum value of water film thickness will increase fast.

Influence of Ground Slag on the Rheology of Mortar

2013 ◽  
Vol 438-439 ◽  
pp. 67-71
Author(s):  
Qian Qian Zhang ◽  
Jian Zhong Liu ◽  
Jia Ping Liu
Keyword(s):  
Film Thickness ◽  
Specific Surface ◽  
Yield Stress ◽  
Surface Area ◽  
Specific Surface Area ◽  
Water Film ◽  
Plastic Viscosity ◽  
Rheological Parameters ◽  
Water Film Thickness ◽  
Binder Ratio

The effects of ground slag with different specific surface area on the rheology of mortar at water-binder ratio of 0.25, 0.28 and 0.30 were investigated, and the combined effects of packing density and solid surface area on the rheology of mortar were evaluated in terms of the water film thickness. The results show that with the increasing of specific surface area of slag (220 m2/kg-784 m2/kg), plastic viscosity and yield stress decrease. The correlations of yield stress and plastic viscosity to the water film thickness are basically linear with high correlation R2 values. The action of the ground slag on the rheology of mortar can be characterized by water film thickness, and with the increasing of water film thickness the rheological parameters decrease.

Measuring Water Film Thickness in a Wet Gas Compressor Diffuser: Design, Calibration, and Testing of Electromagnetic Probes

2017 ◽  
Author(s):  
Craig Nolen ◽  
Melissa Poerner
Keyword(s):  
Film Thickness ◽  
Water Level ◽  
Water Film ◽  
Probe Design ◽  
Two Phase ◽  
Water Film Thickness ◽  
Wet Gas ◽  
Flow Phenomena ◽  
In Series ◽  
Electromagnetic Probes

The distribution of water in the diffuser of a wet gas compressor is not well understood. Measurements of water film thickness across the diffuser surface would improve the understanding of two-phase flow phenomena in wet gas compressors. Electromagnetic probes were designed in order to measure water film thickness in the diffuser of a SwRI-designed wet gas compressor. The probes consisted of two electrode foils plated on a thin insulating substrate, allowing them to be bonded in place without drilling through the diffuser. An AC signal was passed between the electrodes, and the voltage across a resistor in series with the electrodes was recorded. As the water level covering the electrodes increased, the recorded voltage increased. A method of calibrating the probes was developed and used prior to installation in the diffuser. Testing showed the probes to be effective at detecting the presence of water in the diffuser and indicating the general water level. Improvements in probe design, calibration, and installation are needed to provide more precise water film thickness data.

Effects and threshold of water film thickness on multi-mineral cement paste

2020 ◽  
Vol 112 ◽  
pp. 103677 ◽  
Author(s):  
Hengrui Liu ◽  
Xiao Sun ◽  
Hui Du ◽  
Hao Lu ◽  
Yuanshan Ma ◽  
...  
Keyword(s):  
Film Thickness ◽  
Cement Paste ◽  
Water Film ◽  
Water Film Thickness
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